Biofuels feedstock study supports billion-ton estimate

By South Dakota State University | February 09, 2018

Can farmers produce at least 1 billion tons of biomass per year that can be used as biofuels feedstock?

That’s the question that researchers are trying to answer, according to North Central Regional Sun Grant Center Director Vance Owens. The goal is to replace 30 percent of the petroleum consumed in the United States with biofuels.

Analysis of up to seven years of production data gathered through the Regional Feedstock Partnership, established by the U.S. Department of Energy and the Sun Grant Initiative supports the U.S. Department of Energy billon-ton estimate. That amount could be available annually by 2030.

“Regional field trials were conducted for the most promising bioenergy feedstocks,” explained Owens, who worked on switchgrass production before becoming Sun Grant director. “Based on these numbers and other research we’ve done, we would still see over a billion tons available per year as the bioeconomy continues to develop.”

South Dakota State University was the lead institution for the more than $20 million project which began in 2007. The partnership was funded by the U.S. Department of Energy Bioenergy Technologies Office. The project involved researchers from the U.S. Departments of Energy and Agriculture, 35 land-grant universities, Heidelberg University and several industry partners, as well as Idaho National Laboratory, Oak Ridge National Laboratory, and Argonne National Laboratory.

This project helps fill an important information gap in the quest to produce biofuels from nonfood crops. South Dakota farmers could play a role in producing these bioenergy crops and the biorefineries that convert the biomass into biofuel would be built near where those crops are raised.

Results published, data available online

Field trial results and yield projections for herbaceous crops, including switchgrass, energycane, mixed perennial grasses on Conservation Reserve Program land, giant miscanthus and sorghum, as well as the woody feedstocks poplar and shrub willow, are available online in the January issue of GCB Bioenergy. An article on environmental mapping of biomass resources in the continental United States will also be published in that issue.

This partnership came about as a direct result of the efforts of SDSU Vice President Emeritus for Research and Economic Development Kevin Kephart and others in Sun Grant, Owens explained. More than 130 peer-reviewed papers, including field trial results and yield projects related to corn stover, have been published through this project.

The raw data from the field trials will be available for public use and can be accessed at Knowledge Discovery Framework at the U.S. Department of Energy website. “The ramifications of this research will be much greater due to free data access,” he said.

Study duration, collaboration increase value of data, modeling

The duration of this study is unique, Owens pointed out. “Typically these projects last two to three years, but having trials in place for up to seven years is really important in terms of long-term yield potential.” For example, researchers were able to gather data about how potential biofuels crops reacted to the 2012 national drought and how they recovered in subsequent years in some instances. “Though annual crops suffer, perennials can manage through a one-year drought,” Owens explained. “Being able to see this was a tremendous advantage—and something we wouldn’t likely see with only a two-year study.”

Among the herbaceous energy crops, field-scale trials using traditional agricultural equipment were conducted for switchgrass and mixed perennial grasses suitable for use on CRP land, while smaller individual plots were utilized for energycane and giant miscanthus due to a lack of vegetative planting materials for these species.

Crop potential varies by region,” Owens explained. “There’s not one that makes sense everywhere; it’s more of a localized environment.” The nationwide yield potential maps track which crops are best suited to a particular area.

“For example, switchgrass is more productive than miscanthus in some of the northern regions because miscanthus is not as winter hardy. On the other hand, energycane is well adapted and highly productive in the Deep South” he said. In the future, the researchers would like to do side-by-side comparisons of different species across multiple environments to better understand their yield potential.

The model used to estimate yield potential, known as PRISM-ELM, included yield-limiting factors, such as water availability, low-winter and high-summer temperature response, soil pH, salinity, and drainage. Modelers and agronomists from each species group met periodically to exchange information and review yield potential maps.

“This is unique to have input from all the parties involved, which then helps makes the models more reliable,” Owens said. The model for perennial grasses, for instance, had to be adjusted based on the plants’ ability to develop roots deep in the soil profile.